AuNPs@MoSe2 heterostructure as a highly efficient coreaction accelerator of electrocheluminescence for amplified immunosensing of DNA methylation

Electrocheluminescence analysis amplified by coreaction accelerators has experienced breakthrough in ultrasensitive detection of biomarkers. Herein, a highly efficient coreaction accelerator, two-dimensional layered MoSe2 nanosheets loaded with gold nanoparticles (AuNPs@MoSe2 heterostructure), is proposed to enhance the ECL efficiency of Ru(bpy)32+/tripropylamine (TPrA) system. The presence of AuNPs avoids the aggregation of MoSe2 nanosheets, and improves the electrical conductivity of modified surface. The AuNPs@MoSe2 modified electrode also provides a large area for loading of abundant capture probe. MoSe2 as an electroactive substrate can remarkably accelerate the generation of TPrA•+ radicals to react with electrooxidized Ru(bpy)32+, which achieves about 3.4-fold stronger ECL intensity. Thus, an enhanced ECL immunoassay method can be achieved after Ru(bpy)32+-doped silica nanoparticle labeled antibody (Ab2-Ru@SiO2) is captured to the modified electrode via immunological recognition. Using methylated DNA as a target, the immunosensor was prepared by binding capture DNA on AuNPs@MoSe2 modified electrode to successively capture the target, anti-5-methylcytosine antibody (anti-5mC) and Ab2-Ru@SiO2. The proposed strategy could detect 0.26 fM 5 mC (3σ) with a detectable concentration range of 1.0 fM - 10 nM at methylated DNA. This immunosensor showed excellent selectivity, good stability and reproducibility, and acceptable recovery, indicating the broad prospects of the novel coreaction accelerator in clinical diagnosis.